Formerly, ambulances were manned by minimally trained crews with the ultimate goal of getting the patient to a hospital or emergency room as quickly as possible. The vehicles were equipped with very basic equipment, such as back-boards, tourniquets and pressure bandages.
It has become standard practice, in most jurisdictions, to provide emergency medical treatment and rescue through Emergency Medical Service (EMS) with highly trained crews and appropriately equipped vehicles. The vehicles now used for EMS are much more sophisticated than the mere transportation formerly available. The vehicles carry resuscitators, intravenous solution kits, including blood plasma and whole blood, and pharmaceuticals in solid and liquid form. The vehicles also include electrical devices for cardiac treatment, for gathering and recording medical data from the patient, such as blood pressure, pulse rate, electrocardiogram, and pulmonary data, among other things.
Some of the solutions and pharmaceuticals carried on EMS vehicles are time and temperature sensitive. Also, some of the drugs carried in the vehicles are controlled substances and must be used by authorized personnel. Usually, such items are stored at a base facility and loaded on a vehicle for a specific emergency.
Other vehicles are now being used for investigations or research that require a permanent record of the activities, inventories, and parameters of collected items. For example, vehicles used to investigate crime scenes require records to establish chain of custody, as well as, the conditions of the items in custody. Research vehicles, in general, have use for devices that can be used to control temperature and make a historical record of the contents in the vehicle.
Regardless of the specific activity to which the vehicle is dedicated, all the equipment must be operated from the electrical system of the vehicle or from batteries carried with each item of electrical equipment.